In the last month, the measure decreased from 100.1 to 99.5. Scores below 100 indicate more consumers are ‘unconfident’ rather than ‘confident’, according to the research.

According to the index, Britain has been in negative territory since March, with the exception of the 100.1 recorded in July.

Data collected during August found that sentiment on household finances dropped slightly from 90.0 to 89.7, while expectations for the year ahead increased from 89.9 to 91.4.

The measure for job security decreased from 86.4 to 84.4 over the past month and the outlook for the next 12 months rose from 107.8 to 108.9.

Oliver Rowe, director of reputation research at YouGov, said: “A 0.6 point drop is well within the level of volatility we see even in a stable economic climate. We need to watch next month’s data closely to see where the trend leads.”

Kay Neufeld, head of macroeconomics at the Centre for Economics and Business Research, said: “In August, the Consumer Confidence Index’s three-month summer rally came to an end. Forward looking measures of household finances and job security have picked up, suggesting consumers are more optimistic about the state of the economy in a year’s time. Until then, however, the UK economy must overcome a number of hurdles.”

Data for the YouGov/Cebr Confidence Index is collected daily, with 6,000 interviews a month. Respondents are asked about household finances, property prices, job security and business activity over the past 30 days and looking ahead to the next 12 months.